== Setup a new kvm domain fast == === guest setup === or: how to install Debian. Define a shell function {{{ # set up environment setup_env() { echo -n "New hostname: " && export LC_ALL=C && read guest && target="/mnt/target-$guest" && mirror=`cat /etc/apt/sources.list /etc/apt/sources.list.d/debian.list 2>/dev/null | awk '/^deb.*debian/ {print $2; exit}'` && vgdefault=`vgdisplay -c | awk -F: '{print $1;exit}' | sed 's/ *//g'` && echo -n "Volume group? [$vgdefault]: " && read vg && if [ "$vg" = "" ]; then vg="$vgdefault"; fi && echo -n "Use lvm for non-swap partitions? [Y/n] " && read use_lvm && if [ "$use_lvm" = "n" ]; then : SAN, as in the msa2012i at ubcece && : requires that it is already setup && dev_root="/dev/mapper/$guest-root" && dev_boot="/dev/mapper/$guest-boot" && echo "Root device will be $dev_root" && echo "Boot device will be $dev_boot" && echo "Make sure they exist already." && fs=xfs else use_lvm="y" && dev_root="/dev/mapper/$vg-$guest--root" && dev_boot="/dev/mapper/$vg-$guest--boot" && echo "Root device will be $dev_root" && echo "Boot device will be $dev_boot" && fs=ext4 fi && if [ "$vg" != "" ]; then dev_swap="/dev/mapper/$vg-$guest--swap" elif [ -d /SWAPFILES ]; then dev_swap=/SWAPFILES/$guest-swap else echo "No idea how to do swap" && false fi && echo -n "Use a /boot filesystem (strongly recommended)? [Y/n] " && read use_boot && echo "Swap device will be $dev_swap" && echo "fs is $fs" echo "Chosen mirror is $mirror" } }}} And run it {{{ setup_env }}} Then install base: The way we lay out the filesystems by default is that we have one 4g / filesystem, a swap, and a tiny boot filesystem. On the host we make a new LVM logical volume for each of the three. Only the LV that will take the guest's boot will actually be partitioned - into a single boot partition. That's so we can install grub into the MBR and have the system start just like a real system. Root and swap are put directly onto the logical volume, without partitioning it at all. This makes getting to the data from the host easier - no need to run kpartx - and it makes growing trivial. {{{ ####### # install base apt-get install debootstrap debian-archive-keyring kpartx && if [ "$use_lvm" = "y" ]; then if [ "$use_boot" != "n" ] ; then lvcreate -L 128m -n "$guest"-boot /dev/"$vg" fi && lvcreate -L 4g -n "$guest"-root /dev/"$vg" fi && lvcreate -L 4g -n "$guest"-swap /dev/"$vg" && : && if [ "$use_boot" != "n" ] ; then ( echo ',,L,*' | sfdisk -D "$dev_boot" ) && kpartx -v -a "$dev_boot" && mkfs."$fs" "$dev_boot"1 fi && mkfs."$fs" "$dev_root" && mkswap "$dev_swap" && : && mkdir -p "$target" && mount "$dev_root" "$target" && if [ "$use_boot" != "n" ] ; then mkdir -p "$target/boot" && mount "$dev_boot"1 "$target/boot" fi && cd "$target" && debootstrap --variant=minbase --keyring=/usr/share/keyrings/debian-archive-keyring.gpg stable . "$mirror" }}} And finalize the setup: {{{ ####### # finish setup echo "$guest" > etc/hostname && cat > etc/hosts << EOF && 127.0.0.1 localhost # The following lines are desirable for IPv6 capable hosts ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters ff02::3 ip6-allhosts EOF rm -fv etc/apt/sources.list && ( ! [ -e /etc/apt/sources.list ] || cp /etc/apt/sources.list etc/apt/sources.list) (cp -v /etc/apt/sources.list.d/* etc/apt/sources.list.d/ || true ) && ( ! [ -e /etc/apt/preferences ] || cp -v /etc/apt/preferences etc/apt/ ) && apt-key exportall | chroot . apt-key add - && chroot . apt-get update && echo "Apt::Install-Recommends 0;" > etc/apt/apt.conf.d/local-recommends && chroot . apt-get install -y net-tools iproute ifupdown dialog vim netbase xfsprogs && cp -av `readlink -f $dev_root` dev/`basename $dev_root` && DEBIAN_FRONTEND=noninteractive chroot . apt-get install -y grub2 && cat > etc/kernel-img.conf << EOF && do_symlinks = no do_initrd = yes EOF if [ "$use_boot" != "n" ] ; then cp -av `readlink -f $dev_boot` dev/`basename $dev_boot` && cp -av `readlink -f $dev_boot""1` dev/`basename $dev_boot`1 && chroot . grub-install --modules=part_msdos /dev/`basename $dev_boot` && # install a kernel image chroot . apt-get install -y linux-image-2.6-amd64 && sed -i -e 's/^#GRUB_TERMINAL=console/GRUB_TERMINAL=console/' etc/default/grub && echo "(hd0) /dev/`basename $dev_boot`" > boot/grub/device.map && chroot . update-grub && sed -i -e "s#dev/`basename $dev_boot`1#dev/hda1#g" boot/grub/grub.cfg && rm -v dev/"`basename $dev_boot`" dev/"`basename $dev_boot`1" else echo && echo && echo && echo "Hardly tested, expect this to fail." && echo && echo && echo && echo "(hd0) /dev/`basename $dev_root`" > boot/grub/device.map && chroot . grub-install /dev/"`basename $dev_root`" && # install a kernel image chroot . apt-get install -y linux-image-2.6-amd64 && sed -i -e 's/^#GRUB_TERMINAL=console/GRUB_TERMINAL=console/' etc/default/grub && chroot . update-grub fi && sed -i -e "s#dev/`basename $dev_root`#dev/vda#g" boot/grub/grub.cfg && rm -v boot/grub/device.map && rm -v dev/"`basename $dev_root`" }}} And a fstab and a boot loader config {{{ # doesn't work: chroot . update-grub rootuuid=`blkid -s UUID -o value "$dev_root"` && swapuuid=`blkid -s UUID -o value "$dev_swap"` && if [ "$fs" = "ext4" ]; then rootopts="errors=remount-ro" else rootopts="defaults" fi cat > etc/fstab << EOF && UUID=$rootuuid / $fs $rootopts 0 1 UUID=$swapuuid none swap sw 0 0 EOF if [ "$use_boot" != "n" ] ; then bootuuid=`blkid -s UUID -o value "$dev_boot"1` && echo "UUID=$bootuuid /boot $fs defaults 0 2" >> etc/fstab fi cat > etc/network/interfaces << EOF auto lo iface lo inet loopback auto eth0 iface eth0 inet manual pre-up ip link set up dev \$IFACE post-down ip link set down dev \$IFACE EOF }}} Maybe fix/setup networking properly: {{{ vi etc/network/interfaces }}} And set a password: {{{ chroot . passwd }}} Set a nameserver config that works once the VM has booted. Later in the process we will install unbound anyway. {{{ cat > etc/resolv.conf << EOF nameserver 8.8.8.8 search debian.org EOF }}} And unmount: {{{ cd / && if [ "$use_boot" != "n" ] ; then umount "$target"/boot && kpartx -v -d "$dev_boot" fi && umount "$target" && rmdir "$target" }}} === virsh setup === Setup a new kvm domain by creating a new file in /etc/dsa-kvm/`hostname/$guest.xml. * Properly configure hostname * Pick a new uuid ({{{uuidgen}}}) * Setup block devices properly * pick a new and unique mac address (on d.o every kvm host has their own mac address space and the last block is changed for the guests, as in {{{..:..:..:..::}}}. ) * virsh commands: ** {{{virsh help}}} ** {{{virsh define foo.xml}}} ** {{{virsh start foo}}} ** {{{virsh destroy foo}}} ** {{{virsh vncdisplay foo}}} (and ssh -L 5900:localhost:<5900+x> $host and vnc localhost) === post processing === Do not forget to set a sane root password before installing ssh in the new kvm domain. === when stuff goes wrong === To get to the guest data from the host: {{{ setup_env kpartx -v -a "$dev_boot" && mkdir -p "$target" && mount "$dev_root" "$target" && mkdir -p "$target/boot" && mount "$dev_boot"1 "$target/boot" }}} and once you're done: {{{ cd / && umount "$target"/boot && umount "$target" && kpartx -v -d "$dev_boot" && rmdir "$target" }}} Make sure that the filesystem isn't being mounted twice - i.e. never start the guest while the filesystems are mounted, and never mount them while the guest is running.